Chapter 14, Problem 68A

To determine

The speed of the wave.

Answer to Problem 68A

The speed of wave is $3.6\text{m/s}$ .

Explanation of Solution

Given info:

Total number of crests $=12$

  $T=20.0\sec$

  $D=3.0\text{m}$

Formula used:

The formula for the frequency is given by,

  $f=\frac{1}{t}$

The formula for the speed is given by,

  $v=\lambda f$

Calculation:

Calculate the frequency/

  $\begin{array}{c}f=\frac{12}{20}\\ =0.6Hz\end{array}$

Calculate the Wavelength

  $\begin{array}{c}\lambda =2\times 3.0\\ =6.0\text{m}\end{array}$

Calculate the speed.

  $\begin{array}{c}v=\lambda f\\ =6.0\times 0.6\\ =3.6\text{m/s}\end{array}$ .

Conclusion:

Hence, the speed of wave is $3.6\text{m/s}$ .